Efforts will be continued towards the isolation of both drug-resistant and temperature-sensitive mutants of Aedes albopictus cells. With respect to drug-resistant mutants, we shall put emphasis on those which are resistant to inhibitors of protein synthesis. A mutant resistant to methylmercaptopurine riboside has been isolated and will be studied to determine the mechanism of resistance to this drug. More hybrid clones will be obtained and characterized with respect to their response to virus infection. Aedes albopictus cells will be tested for their ability to grow on carbohydrate sources other than glucose. The toxicity of adenosine and guanosine for these cells will be investigated.